1. Technical Field
This invention relates to air conditioning and heating systems for trucks or other large vehicles, and more particularly relates to an auxiliary power plant which is connected to and operates in conjunction with the existing air conditioning and heating system of the vehicle and also serves to warm the engine of the vehicle to enable easy starting of the vehicle engine in cold weather.
2. Description of the Prior Art
Auxiliary systems are known in the prior art for heating a vehicle engine and its fuel line while the engine is not operating. Examples of such prior art are present in U.S. Pat. Nos. 3,877,639, 4,192,457 and 4,448,157.
U.S. Pat. No. 4,454,984 discloses an auxiliary system for heating a truck cab in which the truck storage batteries operate an auxiliary pump.
U.S. Pat. No. 4,531,379 discloses an auxiliary power system for a vehicle air conditioner and heater. The system is designed for an automobile or van. It utilizes a jack shaft assembly equipped with an electromagnetic clutch to transfer power from an auxiliary engine to an existing air compressor of the vehicle when the main engine of the vehicle is not operating.
U.S. Pat. No. 4,448,157 discloses a system including an auxiliary engine for heating the coolant of the main engine, when not in use; however, the disclosed system exhibits several limitations. For example, it teaches the placement of a shut down regulator before the coolant is heated by the heat exchanger. This will cause the auxiliary engine to be overheated long before the shutdown regulator operates. Also the use of T connectors into the radiator outlet, rather than into the engine itself, will only heat the radiator as the non-restricted flow into and out of the radiator will offer less resistance than the thermostatic restriction into and out of the engine itself. As is well known, the thermostat in the engine return line to the radiator closes to stop water flow out of the engine until proper temperature is reached and this will prevent the system from heating the engine as the flow will only be in and out of the unrestricted radiator connections. The coolant also goes through an auxiliary cooling radiator before going back to the main engine. This radiator appears to reduce the heat supply even more.
The objective of the present invention is to improve on the known prior art through provision of an auxiliary power plant for trucks or other large vehicles which is operatively connected with the existing air conditioning and heating system of the vehicle in such a way that the auxiliary power plant can efficiently operate the air conditioning and heating system of the vehicle during such times when the engine of the vehicle is not operating. To enable this, the auxiliary power plant possesses its own engine, alternator, air conditioning compressor, water pump and a heat exchanger which includes heating coils connected in the water cooling circuit of the main engine and being in heat exchange relationship with the exhaust system of the engine of the auxiliary plant.
A further important object of the invention is to provide in an auxiliary power plant of the type mentioned, means for warming the main engine of the truck or other large vehicle when such main engine is not operating, to thereby render easy the starting of the main engine in cold weather after long periods of idleness.
Still a further important object of the invention is to provide in an auxiliary power plant of the type mentioned means for heating the cab of the truck or other large vehicle when the main engine is not running.
Yet a further important object of the invention is to provide in an auxiliary power plant of the type mentioned, means for heating the oil of the truck or other large vehicle when the main engine is not running in order to facilitate the starting thereof.
Another important object of the invention is to provide in an auxiliary power plant of the type mentioned means for applying additional load to the auxiliary engine for increasing the heat output thereof when desired.
Yet another important object of the invention is to provide an auxiliary power plant whose dimensions do not exceed approximately 18".times.18".times.24" and whose weight including its frame does not exceed approximately 200 pounds, thus enabling the power plant to be installed conveniently at available locations on different makes and models of trucks.
Other features and advantages of the invention will become apparent to those skilled in the art during the course of the following description.
As used herein, the word "truck" is not to be taken in a limiting sense, and is intended to apply to any large vehicle, such as a bus, road building equipment, or a military vehicle.